How Long Can You Keep The Oil In a Deep Fryer? (Real Data)

When it comes to deep-frying, there is so much to know about the whole process. One of the most common questions, especially for people new to deep-frying, is how long you can keep the oil in a deep fryer? The answer to this and many more questions you will find when you stick with me!

In this article, I will teach you all the essentials about deep frying and deep-frying oils, but before we get further to the subject, you need to know how long you can keep oil in a deep fryer?

Generally, you can keep oil in a deep fryer for up to a month. However, if it is frequently used, then you should change it every 3 to 14 days. You should change the oil every 3-4 days in restaurant use, so twice a week. In less frequent home use, you should be able to hold it for two weeks.

Obviously, many factors affect the time oil can be held in a deep fryer, yet to be used. So next, I want to help you understand what things take place when determining how long you can keep the oil in a deep fryer and how to extend that duration. There are 4 main factors that we need to understand; let’s start with what you are frying.

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1. Food you are frying

Not all food that you can fry is equal to the oil’s condition. For example, in most cases, if you fry more meat than vegetables which is usually the case, the oil can’t be kept and used as long when comparing to frying vegetables or finger foods such as fries, onion rings, mozzarella sticks, etc.

Especially if a restaurant is frying nearly constantly chicken wings or fish, naturally, you can’t keep the oil as fresh as with veggies.

Also, if the food has a breading of some sort especially if it isn’t as thick as it should be, it will leave a lot of food particles in the oil so you would need to remove them in order to increase the oil’s lifespan. So, where to tell the oil has gone bad? More on that after these 4 factors.

2. What oil you are using

Another factor that determines how long the oil can be kept in a deep fryer, on average, is what oil you are using. As a rule of thumb, canola oil is the best deep-frying oil because it has a high smoke point of 400-450°F (204-230°C) which drastically increases the lifespan of the oil. Also, canola oil is healthy, it has a natural flavor, and it’s quite cheap.

When we compare canola oil to olive oil, for example, it has a far lower smoke point, which means that it is more affected every time it is heated, which leads to faster quality decrease so you couldn’t hold it fresh in your deep fryer as long.

3. Oil filtering

This is an important one if you really want to increase your oil’s hold time in the deep fryer. The oil isn’t necessarily filtered after each use in restaurants because it would be so big time consumer, and it simply couldn’t work. When combined with constant frying, we can now understand why a restaurant’s deep-frying oil needs to be changed at least a couple of times a week.

On the other hand, we home deep fryers can filter the oil after each use without problems, and when that is done, the oil’s lifespan really increases. For example, if you could hold oil in a deep fryer for a month, but you filter it after each use, the time can be increased up to 3 months, which is remarkable. In this case, you really need to monitor your oil’s condition, but if it looks good, it usually is good.

How to filter deep frying oil at home

What you’ll need:

  1. Use your thermometer to see if the oil has cooled down after frying
  2. Use a ladle and pour the cooled oil through the metal funnel with a small strainer or screen into the plastic container
  3. This is done because the filter will separate the larger food particles from the fresh oil, so it keeps its quality.
  4. Close the plastic container and store it in a cool place.

4. Storage conditions

The final major factor in whether you can keep your oil in your deep fryer long or short period of time is how you store it. In restaurants, the unused oil is usually stored in their plastic canisters on a shelf that isn’t in the hottest area in the kitchen as it should. However, the oil in use is usually hot many hours in a row, sometimes both shifts, which take a toll on the oil. So, again, this is yet another factor why restaurant oil needs to be changed so often.

In home use, if you store both of your oils, the one in a canister and the one in a deep fryer, in a chill place and keep a lid on the fryer, you can keep it fresh much longer.

Now, let’s move on to the real determinator of how long you can keep the oil in your deep fryer. This is done by examining the oil, which is really the only way to be sure how long your oil can and had been in the fryer. I have given estimates here, but then the differences are so drastic because of the 4 factors above, so it’s hard to say accurately how long the time can be. Let’s take a look at how to tell if your oil is bad or not.

Read also: Why Don’t Restaurants Use Air Fryers? (4 Reasons)

How can you tell if deep fryer oil is bad?

As a rule of thumb, if you notice small bubbles or foam on the oil’s surface or a fishy and stuffy aroma, it’s a sign that the oil is bad. In addition, when you are frying, and it can’t cook the food without generating smoke, it’s is expired. Finally, if the oil looks dark and dirty, it should be changed.

All these reasons are red flags that tell you the oil has gone bad, and if you still aren’t sure, I have a trick for that. Tell what your gut tells you, and that’s what I always do, and it has never failed me. If you need to second guess whether your oil is good or not, it probably isn’t.

How many times can you use deep fryer oil?

This is a tricky one to answer accurately but there are some great rules to live by. Let’s start with breaded foods.

If you fry breaded foods, the frying times are decreased by half the amount of non-breaded items. If you make the breading yourself and it’s fresh and room temperature, I would fry a maximum of 5 times with the same oil. However, if the breaded foods are frozen, you can add a couple more frying times up to 8.

Again, if the oil still looks good, you can use it more, but if it starts to look bad after the third fry, you should change it. Also, remember to filter the oil after each use if you want to increase the use.

Now the better news, if you fry non-breaded foods such as fries or potato chips, you can easily fry 10 times with the same oil and probably more. The same rules apply for non-breaded foods, which always monitor your oil and see if it is still good.

How to change the oil in a deep fryer?

When it comes to deep-frying, cleaning and changing the oil is really important if you want to maintain food hygiene, increase your oil’s frying times, and the lifespan of your deep fryer. So let’s take a look at how to change and clean your deep fryer.

  1. Turn off the fryer and remember to unplug the power cord.
  2. Let the oil cool off completely. Use a thermometer if needed but don’t rush this step because it’s dangerous.
  3. Remove the oil to a safe place from the fryer’s valve or by hand to a plastic container, for example.
  4. Now, remember to close the drain valve! After that, clean the interior with a cloth and take out the biggest particles
  5. Fill the fryer with water and add Boil Out Cleaner. Read the instructions from the cleaner and add the right amount.
  6. Plug the fryer, turn the fryer on and let the water boil for about 30minutes. After this, turn off the heat.
  7. After the water is cooled, open the valve, drain the excess water to a bucket, scrub the interior with a Deep Fryer Brush and rinse the interior well with water to get the cleaner completely off. After that, close the valve again.
  8. Fill the fryer with fresh deep-frying oil, and you’re ready to fry once again!

There are a lot of steps to the process, but they aren’t overly complicated. Also, you won’t necessarily need to clean your home fryer with the boil-out cleaner, at least every time. However, restaurant fryers aren’t so easily cleaned, and it is hard to reach every corner, so it is important to boil out restaurant fryers.

How much oil should you pour into a deep fryer?

Generally, each deep fryer has its own maximum fill line in the interior of the fryer. Therefore, you should fill the deep fryer with oil to that line. However, if the fryer doesn’t have a maximum fill line, don’t worry. In this case, fill the deep fryer, so it’s 3/4 full.

What can you do with old frying oil?

The old frying oil is always annoying because you really never know what to do with it. At least don’t throw it in the drain because it really can get stuck; it’s bad for the drains and the environment. So instead, I always use sealable bags that can be filled with old frying oil and then be tossed away. Toss-It Bags are a great example of such bags.

Read also: Kitchen Sink Unclogging 101: Make Life Easier

What are the best oils for deep frying?

There are more than a dozen oils that can be used in deep frying, and probably more. However, I love 3 of them the most for various reasons.

Canola oil is a universally loved oil because of its many benefits. First of all, canola oil is neutral-flavored so that it won’t affect the fried food’s natural flavor. Second, it has a higher smoke point than foods require so that it won’t become burnt and smoky either. Finally, canola oil is cheap; therefore, many restaurants use it.

Vegetable oil is another of my personal favorites, and it is ranked as one of the best by most other chefs. Vegetable oil can be used to fry really anything, and it’s no wonder why it has a reputation as a multipurpose oil. Also, it has a high smoke point as well so it can hold extreme temperatures before it starts to burn. Finally, the flavor is quite neutral as well.

Peanut oil is a great oil for deep frying as well; in fact, it has the highest smoke point of these three oils, which is 450°F (232°C). Peanut oil is similar to vegetable oil in many ways because it has many purposes and is healthy.

What is the best temperature for deep frying?

Ideally, the best temperature for deep frying is 350-375°F (176-190°C). You can easily see the current temperature with a thermometer, and with most deep fryers, you can set the temperature by turning the temperature knob.

When we know the ideal temperature that is 350-375°F, we can now start looking at some good deep-frying oils. I have gathered information on many oils from the easy-to-read table below. Check it out!

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OilSmoke point
Canola oil400-450°F / 204-230°C
Vegetable oil400-450°F / 204-230°C
Peanut oil440-450°F / 227-230°C
Coconut oil350-385°F / 175-196°C
Extra virgin olive oil325-410°F / 163-210°C
Corn oil410-450°F / 210-230°C
Sunflower oil440°F / 230°C
Avocado oil520°F / 271°C
Soybean oil450-495°F / 230-257°C
Sesame oil350-410°F / 175-210°C

As we can see, coconut and olive oil aren’t really meant for frying, and some other oils aren’t the best for frying even when their smoke point would be fit for it. I recommend that you stick with canola, vegetable, and peanut oil for frying.

Can a deep fryer catch fire?

Deep fryer can definitely catch fire; even it is a rare occurrence. However, there are a couple of things that often are the cause of it. A frozen turkey can easily catch the fryer in fire because of the high ice content, which tends to be deep and hard to remove. Also, a fryer with no thermostat control will often be dangerous to use, leading to a fire.

When deep-frying, it’s important to keep reason with you, so don’t put water and ice into a deep fryer, and if you have a fryer without a thermostat control, don’t host frying cookouts that last for hours.

Learn more: What Happens When You Put Ice In a Deep Fryer?


In the best-case scenario, you can keep your oil inside of your deep fryer for months, and in the shortest case, it’s half a week at max. Whatever the case may be, you can always extend the oil’s life by storing it correctly, filtering it, and frying more non-breaded foods. I hope that this article was useful to you and you got some insights that you can implement into your real everyday life. If so, I call this article a success!

Here You’ll Find My Favorite Kitchen Equipment.

Thanks for reading this article! I hope that it brought you real value that you can benefit from in your personal life! Here is my top kitchen equipment that I seriously couldn’t live without, and I think they could ease your life as well as they do mine.

  • Knife set: As a chef, I can’t stand dull, poor-quality knives without any design. My absolute favorite kitchen knife set is the Gangshan 3-Piece Knife Set. It comes with a handcrafted 8″ chef’s knife and a 3.5″ paring knife. What I love even more than these flawless knives is the walnut knife block which is incredible and unique.
  • Skillet: In addition to knives and my unwillingness to bargain with its quality is the cookware. My favorite skillet is Le Creuset Enameled Cast Iron Skillet. This particular skillet is 9″ in size, it is heavy, it gets very hot, which is what is required to get a good sear, and it is just beautiful, as are all Le Creuset products. Le Creuset doesn’t need an introduction as a brand, as it is one of the world’s rated brands.
  • Food processor: I remember when I hadn’t a food processor at home. It wasn’t easy! But now, when I use my Ninja BN601 Food Processor, I can make anything super fast, which saves me many hours per week. This food processor has 1000 watts of power and four options, including chopping, slicing, dough, and purees. I also like the middle-sized 9cup (2.1l) bowl as it is big enough yet not too big to look unfitting in my kitchen.
  • Tweezers: Dalstrong Professional Cooking Tweezers are like tongs but much more elegant, thin, and easy to use. They are great for virtually anything, but flipping, turning, and grabbing with them is easy and makes cooking much more fun! These Dalstrgon tongs are titanium coated and very durable. Also, I like the black color instead of the everyday steel.

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Omar Abdalla

I’m the owner of JRS. While I love writing about food, I also enjoy peaceful and relaxed cookouts at home.

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